An external review has found Adelaide's Women's and Children's Hospital to be 20 per cent less efficient than other comparable hospitals and proposed ways to boost its performance.

Consulting firm Deloitte did the review.

SA Health CEO David Swan flagged changes would be made after six weeks of public consultation.

"Longer patient stays in hospital which resulted in greater operating costs were the main reason identified," he said.

"The hospital has implemented a number of strategies to improve efficiency and performance, including reducing unnecessary bed days and lowering nursing agency costs by almost half."

The review proposes cutting 30 beds and reducing the length of patient stays.

It wants staffing to be cut by the equivalent of 85 full-time jobs by the 2015-16 financial year.

Mr Swan said there was no plan for forced redundancies.

He said advances in medicine and technology meant patients needed to be in hospital for less time.

Mr Swan said the length of stay for new mothers could be cut by half a day from the current average of 3.3 days for a normal birth.

"If you go back through time, 20 years ago the amount of time [for] a normal birth was 6-7 days and through the changes of clinical practice, the way we have antenatal care that prepares women a lot better, we have better programs that support people in the community," he said.

"The feedback we have from families is that they really want to get back to their family as soon as possible.

"They want to get back into the family environment to be with their loved ones. Of course no one is going to be discharged before they're clinically ready and are well to go home."

SA Health said if all the review measures were adopted the hospital could expect to save $19.2 million by 2015-16.

It said a further $7.27 million of savings had been identified under current strategies.

SA Health said the Women's and Children's was the latest public hospital to face a review after similar processes led to changes for other Adelaide hospitals.

Nursing and Midwifery Federation official Elizabeth Dabars said the union feared for patient care.

"Why would we be considering a reduction in staffing considering that the staffing levels and mixes used are constructed from SA Health's own staffing standards and any cuts would actually lead to safe and effective care being compromised?" she said.